U.S. patent application number 16/482197 was filed with the patent office on 2020-02-06 for axle box suspension of railcar.
This patent application is currently assigned to KAWASAKI JUKOGYO KABUSHIKI KAISHA. The applicant listed for this patent is KAWASAKI JUKOGYO KABUSHIKI KAISHA. Invention is credited to Fumikazu KOUNOIKE, Takaya ONO, Yukitaka TAGA, Yoshihiro TAMURA.
Application Number | 20200039541 16/482197 |
Document ID | / |
Family ID | 62978400 |
Filed Date | 2020-02-06 |
United States Patent
Application |
20200039541 |
Kind Code |
A1 |
TAMURA; Yoshihiro ; et
al. |
February 6, 2020 |
AXLE BOX SUSPENSION OF RAILCAR
Abstract
An axle box suspension of a railcar includes: a coupler
extending from the axle box in a car longitudinal direction and
including a tubular portion at a tip end portion of the coupler,
the tubular portion opens toward both sides in a car width
direction, the coupler coupling the axle box and a bogie frame; a
core rod inserted into an internal space of the tubular portion, a
pair of protruding portions provided at both respective sides of
the core rod in the car width direction; an elastic bushing
interposed between the tubular portion and the core rod; a pair of
receiving seats at the bogie frame, including a pair of recess
portions and a pair of groove portions, a pair of lids supporting
the pair of protruding portions fitted into the pair of groove
portions, and fasteners fixing the lids to the receiving seats.
Inventors: |
TAMURA; Yoshihiro;
(Kobe-shi, JP) ; TAGA; Yukitaka; (Kobe-shi,
JP) ; KOUNOIKE; Fumikazu; (Kakogawa-shi, JP) ;
ONO; Takaya; (Kobe-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KAWASAKI JUKOGYO KABUSHIKI KAISHA |
Kobe-shi, Hyogo |
|
JP |
|
|
Assignee: |
KAWASAKI JUKOGYO KABUSHIKI
KAISHA
Kobe-shi, Hyogo
JP
|
Family ID: |
62978400 |
Appl. No.: |
16/482197 |
Filed: |
January 16, 2018 |
PCT Filed: |
January 16, 2018 |
PCT NO: |
PCT/JP2018/000921 |
371 Date: |
July 30, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B61F 5/301 20130101;
B61F 5/305 20130101; B61F 5/325 20130101 |
International
Class: |
B61F 5/30 20060101
B61F005/30 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 30, 2017 |
JP |
2017-013773 |
Claims
1. An axle box suspension of a railcar, the axle box suspension
coupling an axle box to a bogie frame, the axle box suspension
comprising: a coupler extending from the axle box in a car
longitudinal direction and including a tubular portion at a tip end
portion of the coupler, the tubular portion being open toward both
sides in a car width direction, the coupler coupling the axle box
and the bogie frame; a core rod inserted into an internal space of
the tubular portion, a pair of protruding portions being provided
at both respective sides of the core rod in the car width
direction; an elastic bushing interposed between the tubular
portion and the core rod; a pair of receiving seats provided at the
bogie frame and including a pair of recess portions and a pair of
groove portions formed by depressing parts of bottom surfaces of
the pair of recess portions; a pair of lids supporting the pair of
protruding portions fitted into the pair of groove portions, the
pair of lids being fitted into the pair of recess portions; and
fasteners fixing the lids to the receiving seats.
2. The axle box suspension according to claim 1, wherein a surface
of the lid which surface is opposed to the bottom surface of the
recess portion and a surface of the lid which surface is opposed to
a lower surface of the protruding portion are continuously formed
on the same plane.
3. The axle box suspension according to claim 1, wherein: each of a
contact surface of the protruding portion and a contact surface of
the groove portion which surfaces contact each other has a
circular-arc surface; and each of a pair of car longitudinal
direction side surfaces of the recess portion includes a flat
surface parallel to a direction in which the fasteners are
fastened.
4. The axle box suspension according to claim 1, wherein with the
protruding portion fitted into the groove portion, the protruding
portion projects toward the lid beyond the bottom surface of the
recess portion.
5. The axle box suspension according to claim 1, wherein: internal
screw holes are formed on the bottom surface of the recess portion
so as to be located at both respective sides of the groove portion;
the fasteners are fastened to the internal screw holes through the
lid.
6. The axle box suspension according to claim 1, wherein each of
the lids has a rectangular solid shape.
7. The axle box suspension according to claim 1, wherein the
coupler is an axle beam.
Description
TECHNICAL FIELD
[0001] The present invention relates to an axle box suspension of a
railcar, the axle box suspension coupling an axle box to a bogie
frame.
BACKGROUND ART
[0002] In a railcar bogie, an axle box is supported by an axle box
suspension so as to be displaceable relative to a bogie frame.
There are various types of axle box suspensions. For example, in an
axle beam type axle box suspension disclosed in PTL 1, an axle
spring constituted by a coil spring is interposed between an axle
box and a bogie frame, and a tip end portion of an axle beam
extending from the axle box in a car longitudinal direction is
supported by receiving seats of the bogie frame. A tubular portion
is formed at the tip end portion of the axle beam, and a core rod
is inserted into the tubular portion through a rubber bushing. A
pair of protruding portions formed on both respective car width
direction side surfaces of the core rod are fitted into fitting
grooves of the receiving seats of the bogie frame from below.
Projecting portions of lids each having a convex shape are fitted
into the fitting grooves so as to support the protruding portions
from below, and base portions of the lids are arranged so as to be
opposed to lower surfaces of the receiving seats. The base portions
are fixed to the receiving seats by bolts.
CITATION LIST
Patent Literature
[0003] PTL 1: Japanese Laid-Open Patent Application Publication No.
2015-107773
SUMMARY OF INVENTION
Technical Problem
[0004] According to the configuration of PTL 1, both the protruding
portion of the core rod and the projecting portion of the lid are
fitted into the fitting groove of the bogie frame. Therefore, the
position of a circular-arc surface constituting an inner surface of
the fitting groove and contacting the protruding portion of the
core rod and the position of a flat surface constituting the inner
surface of the fitting groove and contacting the projecting portion
of the lid need to coincide with each other in the car longitudinal
direction. Therefore, high machining accuracy is required when
forming the above surfaces constituting the inner surface of the
fitting groove through separate steps.
[0005] An object of the present invention is to provide an axle box
suspension which relaxes the requirement of machining accuracy of a
receiving seat and a lid, and therefore, improves productivity.
Solution to Problem
[0006] An axle box suspension of a railcar according to one aspect
of the present invention is an axle box suspension of a railcar,
the axle box suspension coupling an axle box to a bogie frame. The
axle box suspension includes: a coupler extending from the axle box
in a car longitudinal direction and including a tubular portion at
a tip end portion of the coupler, the tubular portion being open
toward both sides in a car width direction, the coupler coupling
the axle box and the bogie frame; a core rod inserted into an
internal space of the tubular portion, a pair of protruding
portions being provided at both respective sides of the core rod in
the car width direction; an elastic bushing interposed between the
tubular portion and the core rod; a pair of receiving seats
provided at the bogie frame and including a pair of recess portions
and a pair of groove portions formed by depressing parts of bottom
surfaces of the recess portions; a pair of lids supporting the pair
of protruding portions fitted into the pair of groove portions, the
pair of lids being fitted into the pair of recess portions; and
fasteners fixing the lids to the receiving seats.
[0007] According to the above configuration, a width of the recess
portion of the receiving seat at which the lid is positioned is
larger than a width of the groove portion at which the protruding
portion of the core rod is positioned, and therefore, the position
of the recess portion and the position of the groove portion are
not required to coincide with each other. Therefore, one of the
recess portion and the groove portion does not have to be machined
in accordance with the width of the other of the recess portion and
the groove portion, and thus, the requirement of the machining
accuracy regarding the relative positional relation between the
recess portion and the groove portion can be significantly
relaxed.
Advantageous Effects of Invention
[0008] According to the present invention, the requirement of the
machining accuracy of the receiving seat can be significantly
relaxed, and therefore, the productivity improves.
BRIEF DESCRIPTION OF DRAWINGS
[0009] FIG. 1 is a side view of an axle box suspension of a railcar
according to an embodiment.
[0010] FIG. 2 is a sectional view taken along line II-II of FIG.
1.
[0011] FIG. 3 is a major-components enlarged view in which a
receiving seat and a lid in FIG. 1 are omitted.
[0012] FIG. 4 is a major-components enlarged view showing work of
fastening bolts of FIG. 1.
DESCRIPTION OF EMBODIMENTS
[0013] Hereinafter, an embodiment will be described with reference
to the drawings.
[0014] As shown in FIG. 1, an axle box suspension 1 of a railcar of
the embodiment is an axle beam type axle box suspension coupling an
axle box 4 to a bogie frame 5. The axle box suspension 1 includes
the axle box 4 accommodating a bearing 3 rotatably supporting an
axle 2. An axle spring 6 constituted by a coil spring is interposed
between the axle box 4 and a side sill 5a of the bogie frame 5, the
side sill 5a being located above the axle box 4. The axle box 4 is
coupled to the side sill 5a by a coupling mechanism 7. The coupling
mechanism 7 includes an axle beam 8 extending integrally from the
axle box 4 toward a bogie middle side in a car longitudinal
direction (car traveling direction). A tubular portion 9 is
provided at a tip end portion of the axle beam 8. The tubular
portion 9 includes an inner peripheral surface having a cylindrical
shape and is open toward both sides in a car width direction. A
core rod 10 is inserted into an internal space of the tubular
portion 9 through an elastic bushing 11.
[0015] As shown in FIGS. 2 and 3, the core rod 10 includes a
columnar portion 10a, a pair of conical flange portions 10b, and
protruding portions 10c. The flange portions 10b are provided at
both respective car width direction sides of the columnar portion
10a. The protruding portions 10c project outward in the car width
direction from both respective side surfaces of the flange portions
10b. Each of upper surfaces 10d of the protruding portions 10c has
a semi-circular surface. Lower surfaces 10e of the protruding
portions 10c are flat surfaces. The lower surface 10e of the
protruding portion 10c is located lower than a center C of of the
circular-arc shape of the upper surface 10d of the protruding
portions 10c.
[0016] In the protruding portion 10c, a width of the lower surface
10e in the car longitudinal direction is smaller than a maximum
width of the upper surface 10d in the car longitudinal direction. A
portion 10f which is part of an outer peripheral surface of the
protruding portion 10c and connects the upper surface 10d and the
lower surface 10e to each other has such a shape that a width of
the portion 10f in the car longitudinal direction decreases as the
portion 10f extends downward. For example, the portion 10f may be a
circular-arc surface that is concentric with the circular-arc upper
surface 10d or may be a tapered surface.
[0017] The elastic bushing 11 is, for example, a rubber bushing.
The elastic bushing 11 includes a cylindrical portion 11a and a
pair of conical flange portions 11b provided at both respective
sides of the cylindrical portion 11a in the car width direction.
The elastic bushing 11 is externally fitted to the core rod 10. The
cylindrical portion 11a of the elastic bushing 11 contacts the
columnar portion 10a of the core rod 10. The flange portions 11b of
the elastic bushing 11 contacts the respective flange portions 10b
of the core rod 10.
[0018] As shown in FIG. 3, the tubular portion 9 of the axle beam 8
is divided into: a first semi-tubular portion 12 provided
integrally with the axle beam 8; and a second semi-tubular portion
13 formed separately from the first semi-tubular portion 12. Inner
peripheral surfaces of the first semi-tubular portion 12 and the
second semi-tubular portion 13 are formed so as to correspond to
outer peripheral surfaces of the cylindrical portion 11a and flange
portions 11b of the elastic bushing 11. The first semi-tubular
portion 12 and the second semi-tubular portion 13 sandwich the core
rod 10 through the elastic bushing 11 and are fixed to each other
by screw rods 14 and nuts 15. By the elasticity of the elastic
bushing 11, the tubular portion 9 is allowed to be displaced
relative to the core rod 10 in front, rear, left, right, upper, and
lower directions.
[0019] As shown in FIGS. 1, 2, and 4, the side sill 5a is provided
with a pair of receiving seats 16 projecting downward. Each of the
pair of receiving seats 16 includes a recess portion 17 and a
groove portion 18. The recess portion 17 is formed by depressing a
lower end surface 16a of the receiving seat 16 upward and is open
toward both sides in the car width direction and a lower side. The
recess portion 17 includes a bottom surface 17a (a ceiling surface
of a space where a lid 19 is arranged) and a pair of side surfaces
17b extending downward from both respective car longitudinal
direction ends of the bottom surface 17a. Each of the bottom
surface 17a and the side surfaces 17b is a flat surface obtained by
flattening machining. In the present embodiment, the bottom surface
17a is a horizontal surface, and the side surfaces 17b are vertical
surfaces. However, the shapes of the surfaces 17a and 17b are not
limited to these. For example, the side surfaces 17b may be oblique
surfaces or curved surfaces.
[0020] The groove portion 18 is formed by depressing part of the
bottom surface 17a of the recess portion 17 upward and is open
toward both sides in the car width direction and a lower side. A
width W2 of the groove portion 18 in the car longitudinal direction
is smaller than a width W1 of the recess portion 17 in the car
longitudinal direction. The protruding portion 10c of the core rod
10 is fitted into the groove portion 18 from below. In this state,
the lid 19 is accommodated in the recess portion 17 so as to
contact the lower surface 10e of the protruding portion 10c of the
core rod 10. The lid 19 is fixed to the receiving seat 16 from
below by bolts B (fasteners), and the protruding portion 10c is
supported by the lid 19 from below. In the present embodiment, a
direction in which the bolt B is fastened is a vertical
direction.
[0021] As shown in FIGS. 1 and 4, regarding the direction in which
the bolt B is fastened, a depth of the groove portion 18 is smaller
than a height of the protruding portion 10c. To be specific, with
the protruding portion 10c fitted into the groove portion 18, the
protruding portion 10c projects toward the lid 19 (lower side)
beyond the bottom surface 17a of the recess portion 17. The groove
portion 18 includes a circular-arc surface 18a formed by curved
surface machining. The circular-arc surface 18a has a semi-circular
shape that is convex upward along the upper surface 10d
(circular-arc surface) of the protruding portion 10c. To be
specific, each of a contact surface of the protruding portion 10c
and a contact surface of the groove portion 18 which surfaces
contact each other is a circular-arc surface.
[0022] The groove portion 18 further includes a pair of tapered
surfaces 18b. The pair of tapered surfaces 18b are continuous with
both respective car longitudinal direction lower ends of the
circular-arc surface 18a. Further, the pair of tapered surfaces 18b
are inclined so as to be away from each other as they extend
downward. Lower ends of the tapered surfaces 18b are continuous
with the bottom surface 17a of the recess portion 17. Internal
screw holes 20 are formed on the bottom surface 17a of the recess
portion 17 of the receiving seat 16 so as to be located at both
respective sides of the groove portion 18.
[0023] The lid 19 includes at least surfaces opposed to the lower
surface 10e of the protruding portion 10c, the bottom surface 17a
of the recess portion 17, and the side surfaces 17b of the recess
portion 17. In the lid 19, the surface opposed to the bottom
surface 17a of the recess portion 17 and the surface opposed to the
lower surface 10e of the protruding portion 10c are continuously
formed on the same plane. To be specific, a flat upper surface of
the lid 19 is a surface opposed to the lower surface 10e of the
protruding portion 10c and the bottom surface 17a of the recess
portion 17. As one example, the lid 19 has a rectangular solid
shape. However, the shape of the lid 19 is not limited to this and
may be, for example, a trapezoidal shape in a side surface.
[0024] Through holes 19a extending in the vertical direction are
formed on the lid 19 at positions corresponding to the internal
screw holes 20. With the protruding portion 10c fitted into the
groove portion 18, the lid 19 is fitted into the recess portion 17,
and the upper surface of the lid 19 contacts the lower surface 10e
of the protruding portion 10c. The bolts B are fastened to the
internal screw holes 20 through the through holes 19a of the lid
19.
[0025] As shown in FIG. 4, when fixing the lid 19 to the receiving
seat 16 by the bolts B, the lid 19 first contacts the lower surface
10e of the protruding portion 10c before the bottom surface 17a of
the recess portion 17. To be specific, at the moment when the lid
19 is fitted into the recess portion 17 from below, and the upper
surface of the lid 19 starts contacting the lower surface 10e of
the protruding portion 10c, a gap having a distance L exists
between the lid 19 and the bottom surface 17a of the recess portion
17. In this state, by further fastening the bolts B, the lid 19
presses the protruding portion 10c upward, and therefore, the
protruding portion 10c is strongly held between the groove portion
18 and the lid 19.
[0026] To be specific, the pressing force generated by the lid 19
when fastening the bolts B acts on the lower surface 10e of the
protruding portion 10c more preferentially than on the receiving
seat 16. Then, contact pressure between a lower surface of the
groove portion 18 and a top surface of the protruding portion 10c
is higher than contact pressure between a side surface of the
groove portion 18b and a side surface of the protruding portion
10c. Therefore, load acting on the core rod 10 in the car width
direction can be received by frictional force between the groove
portion 18 and the protruding portion 10c. Since the shape of the
groove portion 18 is a circular-arc shape, the generation of the
stress concentration can be suppressed even at a load path of the
bogie frame 5.
[0027] According to the above-described configuration, the width W1
of the recess portion 17 of the receiving seat 16 at which the lid
19 is positioned is larger than the width W2 of the groove portion
18 at which the protruding portion 10c of the core rod 10 is
positioned, and therefore, the position of the recess portion 17 in
the car longitudinal direction and the position of the groove
portion 18 in the car longitudinal direction are not required to
surely coincide with each other. On this account, the requirement
of the machining accuracy regarding the relative positional
relation between the recess portion 17 and the groove portion 18
can be significantly relaxed. Especially, in the present
embodiment, since the groove portion 18 has a circular-arc surface,
and the recess portion 17 has a flat surface, these surfaces are
formed through separate steps. However, since the requirement of
the positional accuracy between the machining of the circular-arc
surface and the machining of the flat surface is relaxed, the
effect of facilitating the machining becomes significant.
[0028] With the protruding portion 10c fitted into the groove
portion 18, the protruding portion 10c projects toward the lid 19
beyond the bottom surface 17a of the recess portion 17. Therefore,
the protruding portion 10c can be strongly held by the lid 19 and
the groove portion 18 of the receiving seat 16. Further, in the lid
19, the surface opposed to the bottom surface 17a of the recess
portion 17 and the surface opposed to the lower surface 10e of the
protruding portion 10c are continuously formed on the same plane.
Therefore, as compared to the case of using a lid having a convex
upper surface, the generation of local stress at the lid 19 can be
suppressed. Further, since the lid 19 is only required to be fitted
in the recess portion 17, the requirement of the positional
accuracy can be relaxed, and the machining and production of the
lid 19 can be easily performed. The internal screw holes 20 for
fastening the bolts are formed on the bottom surface 17a of the
recess portion 17. Therefore, the lid 19 does not have to
significantly protrude from the receiving seat 16, and compact
appearance can be realized as compared to a case where the internal
screw holes 20 are formed on the lower end surface 16a of the
receiving seat 16.
[0029] The present invention is not limited to the above-described
embodiment. Modifications, additions, and eliminations may be made
with respect to the configuration of the present invention. For
example, the portion 10f connecting the upper surface 10d and the
lower surface 10e in the outer peripheral surface of the protruding
portion 10c of the core rod 10 may be a surface which is not
inclined relative to the direction of the fastening of the bolt B
and is parallel to the direction of the fastening of the bolt B.
The groove portion 18 does not have to include the tapered surfaces
18b and may include only the circular-arc surface 18a. The tubular
portion 9 may have a two-piece structure including front and rear
pieces, a two-piece structure including upper and lower pieces, or
an integrated structure.
[0030] The direction in which the bolt B is fastened is not limited
to the vertical direction and may be a direction inclined with
respect to the vertical direction. The side sills may be omitted
from the bogie frame, and the receiving seats 16 may be provided at
the cross beam of the bogie frame. In this case, a plate spring
extending in the car longitudinal direction may be used as the axle
spring instead of the coil spring, a middle portion of the plate
spring may support the cross beam, and both longitudinal direction
end portions of the plate spring may be supported by the axle
boxes. The core rod 10 is fitted into the groove portion 18 from
below. However, the positions of the groove portion 18 and the lid
19 may be vertically reversed, and the core rod 10 may be fitted
into the groove portion 18 from above. The axle box suspension is
an axle beam type as one example in the present embodiment, but the
present embodiment is not limited to this, and various types may be
used.
REFERENCE SIGNS LIST
[0031] 1 axle box suspension [0032] 4 axle box [0033] 5 bogie frame
[0034] 8 axle beam [0035] 9 tubular portion [0036] 10 core rod
[0037] 10c protruding portion [0038] 10d upper surface
(circular-arc surface) [0039] 11 elastic bushing [0040] 16
receiving seat [0041] 17 recess portion [0042] 17a bottom surface
[0043] 17b side surface [0044] 18 groove portion [0045] 18a
circular-arc surface [0046] 19 lid [0047] 20 internal screw hole
[0048] B bolt (fastener)
* * * * *